1. Field of the Invention
This invention relates to a liquid preparation for oxidation hair dyes. Preparations of the type in question consist of hair dye intermediates and a carrier suitable for application to the hair. Preferred carriers are cream-form emulsions of the water-in-oil type and aqueous or aqueous-alcoholic solutions of soaps.
2. Statement of Related Art
After addition to the aqueous solution of the oxidizing agent required to develop the oxidation dyes, oxidation hair dye bases of the type in question based on liquid, aqueous or aqueous-alcoholic soap solutions form a thickly liquid to gel-like, ready-to-use hair dye preparation.
It is also known that water-soluble cationic polymers can be added to hair dye preparations. The hair-cosmetic properties of the treated hair are improved in this way. At the same time, a hair-conditioning effect is obtained.
However, difficulties are involved in the production of liquid preparations for oxidation hair dyes containing soaps and cationic polymers because preparations such as these tend to become inhomogeneous and, in some cases, to become cloudy and to form precipitates and sediments immediately after their production or after prolonged storage. In addition, the hair-conditioning effect of the product is lost through interaction of the cationic polymer with the soap.
On the other hand, however, oxidation hair dye preparations based on liquid, aqueous or aqueous-alcoholic soap solutions represent an advantageous form of conditioning because, after addition to the aqueous solution of the oxidizing agent, they form a thickly liquid to gel-form dye preparation which adheres to the hair after application.
In order, therefore, to enable soaps and cationic polymers to be incorporated in hair dye bases, it was proposed in DE-OS 35 00 877 to use either dicarboxylic acids in the form of their water-soluble salts or amines corresponding to general formula (D) ##STR2## in which R.sup.1 is a C.sub.8-22 alkyl group and R.sup.4 and R.sup.5 independently of one another represent hydrogen or an acyl group having the formula R.sup.6 --COO--, where R.sup.6 is a C.sub.1&lt; alkyl or alkenyl group; b=2 or 3; and x and y are numbers of 0 to 5, the sum (x+y) being from 2 to 6, in order to stabilize the formulations.
Although the aqueous systems containing soap and cationic polymer can be stabilized by the substances mentioned with the conditioning properties of the cationic polymers intact, there remains the disadvantage that relatively high concentrations, particularly of the amine, have to be used to obtain the high viscosities required for stabilization.
Accordingly, the problem addressed by the present invention was to find stabilizing substances which, even when used in relatively low concentrations, would lead to a high increase in the viscosity of the formulation.